Breast cancer is a very common and feared problem where current therapy is inadequate for patients with metastatic disease. Recently, there has been FDA approval for a monoclonal antibody called Herceptin which given alone results in a small response rate for patients with metastatic breast cancer. We have been working with the Herceptin antibody in the laboratory. We have found that Herceptin is a potent of antibody-dependent cellular cytotoxicity. This mechanism of targeting killing of breast cancer cell lines is through the Fc receptor of natural killer cells. We have treated over 75 patients at the University of Minnesota with the immune stimulating drug interleukin-2 (IL-2). We know that IL-2 stimulates in vivo expansion of natural killer cells. We have already demonstrated that these natural killer cells have functional Fc receptors which should be capable of binding Herceptin. It is our hypothesis that this combined therapy will give better therapeutic responses than Herceptin alone. The safety of this approach and the possible efficacy will be explored in this trial.